In the recent past it has become more and more important for consumers that aqueous cleansing compositions are high foaming as well as mild. These combined properties are especially useful if the cleansing compositions are to be topically applied to human skin and hair. Consequently, efforts have been made to provide washing products, such as hair shampoos, shower gels and facial wash foams, showing these two properties. The major problem to provide such products resides in the fact that both properties tend to be mutually incompatible. While high lathering surfactants are generally very harsh, mild surfactants tend to give insufficient lather.
In the past attempts have been made to overcome these problems by combining harsh surfactants generating sufficient lather with very mild co-surfactants.
U.S. Pat. No. 3,728,447 (C J Patterson) discloses hair shampoo compositions containing fatty acid lactylates or glycolates while the cleaning actions of these shampoos is satisfactory the foam remains minimal. In order to achieve higher foaming action it is described to incorporate booster surfactants, such as sodium lauryl sulphate or triethanol amine lauryl sulphate, in the shampoo compositions. However, these booster surfactants are causing a high degree of irritancy when applied on human skin.
WO 91/09923 describes compositions comprising an ultra mild surfactant and a foam enhancer. The ultra mild surfactant is an alkyl glyceryl ether sulfonate (AGS) which has a hydrophobic group containing a linear alkyl chain containing from about 7 to 9 carbon atoms. Conventional foam boosters such as amine oxides and water soluble halide salts are added to improve lather creaminess, volume and stability.
EP-A-224 796 (Kao) describes a detergent composition comprising (a) a phosphate surfactant and (b) an acyl lactylate having an acyl group containing 12 to 18 carbon atoms. Specific examples for such combinations are mixtures of lauryl phosphate and stearoyl lactylate, isostearoyl lactylate and lauroyl lactylate, respectively.
U.S. Pat. No. 4,761,279 (Eastman Kodak) discloses shaving cream formulations comprising salts of C.sub.14 -C.sub.22 acyl lactylates, saturated monoglycerides, propylene glycol monoesters and humectants.
It has now been discovered that a combination of specific short-chain surfactants with specific long-chain surfactants provides mild cleansing compositions with the added attribute that by using these compositions a high degree of lather is generated. Unexpectedly, these properties have been achieved by combining very mild surfactants, which on application on their own give unsatisfactory lather in terns of foam volume. The synergistic effect obtained by combining the specific short-chain and the specific long-chain surfactant is described later herein.